Samples, in particular tissue samples, are usually processed with reagents and then cut into thin sections so that they can be examined with the aid of a microscope. The tissue samples are processed semi or fully automatically preferably in a tissue processor and in particular are successively exposed to the various reagents. In this process, the tissue samples are introduced into a device for processing tissue samples, in particular a retort. Thereafter, the retort is successively filled with the various reagents for clearing, dehydrating and fixing of the tissue samples so that the tissue samples are exposed to the respective reagents. In almost every process step it is important that the tissue samples are completely covered with reagent and thus are completely exposed to the respective reagent. For this reason, filling level sensors are usually arranged in retorts. These may be damaged by cleaning tools or baskets for receiving tissue samples. Further, filling level measurements may be skewed by the baskets.
JP 2001194276 A shows a tissue processor comprising a processing room which communicates with a chamber in which a filling level sensor is arranged. The filling level sensor comprises an ultrasonic transmitter and an ultrasonic receiver which are each arranged at different sides of the chamber.
From U.S. Pat. No. 3,526,203, a tissue processor for fixing, dehydrating and clearing tissue samples is known. For receiving the tissue samples, the tissue processor has a processing chamber which communicates with containers in which reagents are stored. Liquid control units are provided with the aid of which predetermined amounts of reagents can be supplied to the processing chamber.
A further tissue processor is described in US 2008/0220468 A1. The tissue processor comprises two retorts, wax baths, reagent containers, a pump and a valve. With the aid of the valve, the reception of the reagents into a processing room of the tissue processor is controlled. Filling level sensors are arranged in a wall of the processing room.
U.S. Pat. No. 5,560,956 A shows a tissue processor comprising a process chamber and at least one reservoir for receiving a processing reagent. Means are provided with the aid of which reagents are driven from the reservoir to an auxiliary reservoir and from the auxiliary reservoir to the process chamber.